1. Field of the Invention
The present invention relates to increased fuel efficiency and greater driving safety by deflecting and otherwise altering the airflow underneath the trailer of a truck trailer rig or the like.
2. Description of the Prior Art
It is well known that the fuel efficiency of any motor driven vehicle is directly related to the vehicle's aerodynamic structure and the amount of atmospheric turbulence caused by the movement of the vehicle. The greater the air turbulence created by the vehicle the greater the resistance, and the more fuel required to move the vehicle. In today's economy, fuel efficiency is of major concern and is particularly relevant when considered in terms of large tractor trailers used for transporting goods wherein the cost of fuel consumed moving the goods directly affects the market price of the goods.
As the trailer of a large tractor trailer is pulled forward by the tractor, a great deal of turbulence is created underneath the trailer as the vehicle disturbs the air. This turbulence results in the increased resistance to forward movement of the trailer and thus lower fuel efficiency.
Recognizing this problem, McErlane, U.S. Pat. No. 4,262,953 shows a deflector panel of compound convexity mounted just forward of the rear axle or axles of a tractor drawn trailer. The purpose of the McErlane deflector panel "is to direct as much air as possible downwardly and rearwardly for the airstream to pass between the innermost vehicle wheels to the region behind the rear of the vehicle." So directing the airstream is said to reduce "the negative pressure or vacuum in the region of the vehicle where differential pressure has the greatest net vehicle retarding effect, that is, at the rear of the vehicle."
Although fuel efficiency has become a primary concern in the recent decade because of fuel cost, a second major consideration is that of increasing the safety of operation of tractor trailer rigs, particularly from the point of view of safety of other motorists sharing the road with such rigs. A major disadvantage of tractor trailers on the highway is that, unaltered, the turbulent air flow beneath and behind a tractor trailer is generally in a direction transverse to that of the movement of the tractor trailer. This means that in wet or snowy conditions, mist and/or snow is thrown laterally of the trailer causing a vision and turbulance problem for any motorist passing or being passed by the rig. To combat these problems, Grout, Sr. et al, U.S. Pat. No. 3,743,343 discloses a baffle means to be mounted on the undercarriage of the trailer forward of its rear axle(s) which channels the airflow toward the rear and in the direction generally perpendicular to the rotational axes of the wheels, to mitigate the turbulence discharge from beneath the trailer in a direction generally transverse the trailer's movement. Besides the baffle means mounted on the sides forward of the rear axle the Grout patent also discloses a so-called "coagulating means" which is mounted to the undercarriage of the trailer rearwardly of the rear axle and which is designed to gather any turbulent discharge and direct it downwardly towards the road or pavement, thus attempting to minimize lateral discharge.
Also known are airstream deflectors for tractor trailer rigs which are mounted on the top of the tractor or on front of the trailer above the tractor, some of which are remotely controlled in deflection attitude by dual acting air cylinders.